blot

North·ern blot a·nal·y·sis

a procedure similar to the Southern blot analysis, used to separate and identify RNA fragments; typically through transferring (blotting) RNA fragments from an agarose gel to a nitrocellulose filter followed by detection with a suitable probe.

[coined to distinguish it from eponymic Southern blot a.]

blot

(blot) a technique for transferring ionic solutes onto a nitrocellulose membrane, filter, or treated paper for analysis; also used to describe the substrate containing the transferred material. For specific techniques, see under technique.

blot

(blŏt)

n.

The Northern, Southern, or Western blot analyses.

blot

1 a technique for transferring electrophoretically separated components from a gel onto a nitrocellulose membrane, chemically treated paper, or filter for analysis. It is frequently used to analyze genetic material.

blot

noun A nitrocellulose or nylon membrane bearing a biomolecule of interest—e.g., DNA, RNA or protein—transferred to the membrane from an electrophoretic gel by either osmosis or vacuum; after transferring the molecule of interest, the membrane is bathed in a solution containing a “mirror-image” of the molecule already on the membrane, producing a hybridisation.

verb To perform any of a number of similar techniques used to analyse biologic molecules. Mixtures of biomolecule—DNA, RNA or protein—fragments are separated by electrophoresis through a polymeric (agarose or polyacrylamide) gel; the separated components are then transferred to a membrane where they are immobilised, analysed and visualised by various techniques including antibody binding and DNA hybridisation.

Southern blotA technique for identifying the presence or absence of a segment of DNA in a sample; the procedure begins by partial enzymatic digestion of nucleic acids, cutting the DNA at specific sites by any of a number of restriction endonucleases, each of which recognises and cuts at a 5- or 6-nucleotide sequence. For instance, HindIII, from H influenzae, cuts DNA at all sites bearing the nucleotide sequence A/AGCTT at the mirror image sites on the 2 DNA chains between the 2 adenines A/A, resulting in a mixture of DNA fragments of varying lengths measuring up to 30 kD, which is then electrophoresed in an agarose gel and transferred to a membrane. Because the DNA on the membrane is single stranded, it has a high affinity for its complementary strand. The final step in the blot is to radioactively “tag” the complementary DNA (Southern blot, after Dr E. Southern), RNA (Northern blot), protein (Western blot), DNA-protein hybridisation (Southwestern blot), and RNA-protein hybridisation (Northwestern blot).

Dot blotDNA, RNA, or protein are dotted directly onto a membrane support, and form discrete spots.

North·ern blot a·nal·y·sis

(nōr'dhĕrn blot ă-nal'i-sis)

A procedure similar to the Southern blot analysis, used mostly to separate and identify RNA fragments; typically done through transferring RNA fragments from an agarose gel to a nitrocellulose filter followed by detection with a suitable probe.

[coined to distinguish it from eponymic Southern blot a.]

South·ern blot a·nal·y·sis

(sŭdh'ĕrn blot ă-nal'i-sis)

A procedure to separate and identify DNA sequences; DNA fragments are separated by electrophoresis on an agarose gel, transferred (blotted) onto a nitrocellulose or nylon membrane, and hybridized with complementary (labeled) nucleic acid probes.

West·ern blot a·nal·y·sis

(wes'tĕrn blot ă-nal'i-sis)

A procedure in which proteins separated by electrophoresis in polyacrylamide gels are transferred (blotted) onto nitrocellulose or nylon membranes and identified by specific complexing with antibodies that are either pre- or post-tagged with a labeled secondary protein. See also: immunoblot Synonym(s): Western blot, Western blotting.

[coined to distinguish it from eponymic Southern blot a.]

zoo blot a·nal·y·sis

(zū blot ă-nal'i-sis)

A procedure using Southern blot analysis to test the ability of a nucleic acid probe from one species to hybridize with the DNA fragment of another species.

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